Bagmaking machine



March 2, 1954 L. MORAVEC ETAL BAGMAKING MACHINE 3 Sheets-Sheet 2 FiledNOV. 7, 1952 INVENTOR MO/QAVEC GAIVS LAD/.FLHV ALFRED BY 6 5}; 7o-vu}r1114 ATTORNEYS March 1954 L. MORAVEC ET AL 2,670,783

BAGMAKING MACHINE Filed Nov. 7, 1952 3 Sheets-Sheet 5 FIG. 4.

INVENTOR LXID/SLAV MOE/H452 ALgPED 6 411/6- Q46 ATTORNEYS Patented Mar.2, 1954 .BAGMAKING MACHINE Moravec ;.and Alfred Gan s, Elmhurst, N.'rY.,:assignorsator Roto Bag Machine" Corporation, NewYork', Y.

Appllcation"November 7, 1952, Serial No. 319372 11 Claims.

7 This invention relates to improvements in 'bag making machines; andparticularly to an improved machine for making' bags'fromso+calledplastic materialssuchas polyethylene and-cel- I'ophaneyor fromothenfiexible'sheet material.

lnthe typeof machine with which the" present invention is concerned, acontinuous :flattene'd tube of flexible thermoplastic *material is heatsealed along regularlyspaced lateral lines to divide the tubeintoindiv'i'dual compartments. The compartments or sections thus formedthen are separated by cutting thetube crosswise adjacent eachlateral'seal toprovide containers that are open atone-end'-and-closedatthe other by the lateral" seals.

In the'past, it 'has' beencommon practice in machines of this'type tobring the" plastic ma- "terial toa completestop eachtime-a lateral heat"seal is to'be made. "of coursegis a time consuming operation-making'itdiflicult toat- .tain high production-rates. "On' theotherhan'd, variousattempts to make lateral' seals in a continuously'mo ving plastic tubehave'not been en- "tirely successful. 'It is, accordingly-"among theobjects "of the present invention to provide an improved "apparatus "for'-making lateral seals' in -a continuously movingstrip'of relativelyresilient material with a high degree of precision, insuring strong,uniform bonds and with i the dimensi'ons'and spacing of the'sealsheld-toweryclose tolerances.

In accordance with a preferred embodiment "of the invention,the-foregoing and'other rlate'd objects are attainedina heat sealingapparatus wherein a moving tube of plastic material is re- "currentlypressed" between-a movable 'heateil bar 'andamoving resilient surface,with the heate'd bar being "firmly held to the moving surface at thepoint of first contact*by 'clamping members which are mountedtomovewith-{thheated bar and clamp against the movingtirbe and-backingsurface. This arrangement not -only *in'sures against heater slippageand =consequent distortion'of the heat" seal,"butalsoprevents-stretchingor overlap of the moving plast-ic tube. 'At-the end of "each' heatsealing pass, theheated "bar and associated clamping members arereturned smoothly to 'theiroriginal position in readiness for thenext'sealingipass. "Inaccordance-with a further feature of the"invention, "provision is .made lie): supplying electricheating currentto lthe heated bar without the usaof slidingcontacts and yet withoutinterruption of the'el'ectriccircult at any point in thetravelofthheatedhar.

A more complete linderstandingofthe inventi'on can be 'had'by' referencetotheiollowing' description of an'illustrative embodimentthereof, whenconsidered in 'connectionwith the accompanying drawings, in which:

Figure lis a schematic diagram showing 'the movement of material through-a bag-making machine embodying the invention;

Figure'z is anenlargedside elevation'of-the heat sealing mechanism inthe machine of Figure 1;

Figure 3 is'a sectional view ofthe heatseaI- ing mechanism of Figure2,-ta-ken'on'the line 3--3 of Figure 2;

Figure 4 is a sectional view, dfthe-heaitefbar and the clamping membersin the heat sealing mechanism, taken on'the line 4 4"of -Figure 3;

Figure 5 is a view,'on the line5- '-5 df-Figure-B, of the cam wheel-inthe'heat sealing 'drivemech- 'anism;

Figuredis a'sectional view'ofthe camming yoke in the same drivemechanism, taken omthe line fi-tof Figure-'3yan d Figures 7-9 areenlarged fragmentary "sectional views of'theheat sealingmechanismdnsequential operating positions, all taken on'lines "corresponding to theline' T-'T of Figure 4.

As shownin Figure 1 of the 'drawingsa bagmaking machine embodying the'present "invention may comprise drive rollers l 0 "feedingaffiat tube[2 of plastic material through the'ma'chine rollers 10 through pressurerollersZ! vtoia pair of preheating rollers 24 and 26,. I-Ierei the tubeI"! is heated -'sli.ghtlypin#preparation'for .theilateral-heatsealingzoperation-with"whichrithe pres- "ent invention isprimarilyconcerned.

From the preheatingrollers' fl and- 76, the tu'be l2 passes over a smallguide roller- 28 and then partially around a relatively large "cylinder:30, referred to hereinafter as the sealing "cylin- 'der. sealingcylinder 39, thetube 12 is-sealedlateral- During the course of 1 itstrave1 over 'the ly at regularly spaced intervals I by a a heatsealing=mechanism 32. Thus as the tube 3 [2 leaves the--cylinder -31),it will'be divided-orcompartmented by the lateral seal lines intouniform rectangular sections.

The compartmented tube 12 leaving the cyiinder then passes over astripping roller is and through drive rollers 36 to a rotary cutter 38.Here the tube is sheared between a fixed blade 40 and a rotating blade42 into sections of equal length, corresponding to the spacing betweenthe lateral seals applied at the sealing cylinderi Each separatedsection thus forms an individual bag which is sealed across the bottomby the lateral seal. The bags thus formed are delivered by a shortconveyor belt at to a stacking tray 66.

From the foregoing brief description of the machine, it can beunderstood that the operation performed at the heat sealing cylinder 3%)involves a number of problems. The sealing mechanism 32 must be arrangedto seal the moving tube [2 at precisely spaced intervals. Otherwise, thebags delivered to the stacking tray may be sealed at varying positionsintermediate the ends, or they may be delivered irregularly as sectionssealed at both ends mixed with sections open at both ends.

At the same time, it should be kept in mind that the sealing operation,unlike the cutting operation, for example, cannot be an instantaneous orquick-contact step. Rather, the tube walls must be held together andheated for an appreciable interval so that the plastic material cansoften and flow together to form a uniform, permanent bond.

Again, it is essential that the heating mechanism engage the moving tubefirmly, without slippage. Otherwise, the lateral seals will be of unevenwidth, or may even failto form due to insufficient heating along anygiven line. Furthermore, the moving tube must not be pulled or stressedin any way while being sealed, as it can easily be deformed in itspartially heated condition.

As shown diagrammatically in Figure 2, the heat sealing mechanism 32 inthe machine of Figure 1 is mounted for rotation about the axis of thesealing cylinder 39 so that the mechanism 32 is movable from a restposition (shown in full-1ines in Figure 2), approximately 45 degrees offthe vertical and below the cylinder to a second higher position (shownin dotted lines in Figure 2) approximately 120 degrees counter-.clockwise around the cylinder periphery from the rest position. Asexplained more fully hereinafter, this rotational movement is obtainedby moving the mechanism 32 radially into engage- .ment with the movingcylinder, thereby causing the mechanism to ride up on the cylindersurface. During this upward travel, the plastic tube is clamped betweenthe cylinder surface and a position in the rotational travel, themechanism 32 is released from engagement with the cylinder surface andfalls back by gravitational force .to its original rest position.

Considering, now, the details of the heat sealing apparatus, in Figure 3the sealing cylinder 36 is shown mounted for rotation on bearings 48 ona shaft 59. The shaft 50 also is rotatably mounted in bearings 52 in apair of upright supportmembers 54. The cylinder 60 is covered by a pad55 of the neoprene, silicone rubber, or similar resilient material,providing a resilient backing surface for the heat sealing operation. Adriving sprocket 56 is secured to one end of the cylinder 30 toaccommodate a drive chain (not shown) which is driven by the mechanismthat operates the drive rollers and the cutter mechanism.

The heat sealing mechanism 32 includes a heated bar 58 mountedv betweena pair of clamping pads 60 (see Figure 4) on a pair of cam rods 62. Thecam rods 62 are slidably mounted in holes 64 in the shaft 50, atopposite ends of the cylinder 30, so that the mechanism 32 can be movedradially with respect to the cylinder 36.

Therods 62 are arranged to be moved radially through the shaft 50 by acamming mechanism which includes a second shaft 66, mounted below thesealingcylinder. shaft 50 in bearings 65 in the support members 54. Theshaft 65 is arranged to be rotated in synchronism with the rotation ofthe shaft 59 by suitable drive means (not shown). Keyed to this secondshaft 66 are a pair of cam wheels 10', each carrying a laterallyprotruding cam segment 12. I

Above thecam shaft 66, a pair of levers M are mounted to pivot laterallyon bracketsl6 in response to the action of the cam segments l2 ridingagainst cam follower rollers It! on the lowerends of the levers 14. Theupper ends of the levers M are yoke-shaped (see Figure 6), and extendpartially around collars that are slidably mounted on the sealingcylinder shaft 50. From the fingers of the yokes, rollers 82 extendinwardly into annular grooves formed by flanges 84 on the surfaces ofthe slidable collars 86.

A pair of bell-crank levers 86 are pivotally mounted in support brackets90 (Figure 6) fixed to the shaft 59 immediately adjacent the slidablecollars 80. The bell cranks 86 are connected at one end by links 92(Figure 3) to the cam rods 62, and at the other end ride against theinnermost surface collar flanges 84.

It will now be evident that upon rotation of the cam shaft 66, the camsegments 12 will ride over the cam follower rollers 18, pivoting thelevers 14 and causing the collars 60 to slide inwardly toward therespective ends of the sealing cylinder 30. A portion of the undersideof each collar 89 is cut away adjacent the bell crank supports 90 sothat the collars can move in the man ner just stated. Actually, thecollars 36 extend partially around the supports 90 in all positions ofthe collars, so that the collars are free to slide but not to rotate onthe shaft 50. The purpose of this arrangement is explained hereinafter.

As the collars 80 slide inwardly, they will force the bell cranks 86 topivot, moving the cam rods 62 radially in a direction to draw themechanism 32 toward the sealing cylinder surface.

As was previously noted, it is extremely important that the heated bar58 be held securely at its original point of contact with the cylindersurface. The arrangement of the clamping members which accomplish thisholding action, to.- gether with the-details of the heated bar mounting,will now be described.

The parts carried by the cam rods 62 include a spacer bar 94, held nearthe outermost ends of the rods 62 between nuts 96. .Inwardly from thespacer bar 94 toward the cylinder 39, the heated bar 58 is suspendedfrom a support member' 91 that is 'slidable on the rods 52 between fixedstops 98 and the spa'cer'bar nuts 96. The heater support 91 normally isheld against the steps 98 by springs I00. Q

The bar 58' preferably is heated electrically,

sac-2mm by: means; ofz. as :-caile'di. ca -Landsa type:- heaterc I 02:(seeifiiguneszviz andzT-ei T1 fittingeenda wise the bar: 53; In: orders?to: carry 'lieatingz current to the heater I02 continuously? withoutinsulation: difficulties and'i other: complications,

tliezheat'er IDZFisITcOIlIlsctBd to receive aahelically: woundresilient; -ml1lti'i-COIIdUOtOIYCab1e? I .042". that: extends :fiom.awclamp: I'M-3onionsrofrtheasupports: 54:; (see: Figure; 2*)5, at: a:point: near thersealing: wlirrderrshaitl 50 ,.t'0;-'a':h0l:.. [Mi-in one:GIIIEliZOifFthej; lieatedxbatsupportmember:9J2 lti iszfoundi thati a;helicallw wound; cable: of: thisctypej will; with;- s-tandithe:rotational; and: reciprocating; motion:of-rtheeheatedibarpraotimlly:indefinitelytwithoutz breaking;

pair" at support: blocks: M 0.? (Figure 8.9 arefi'xed.tDlthE'ZTIUdSEGkHHjflCBIlt the :stopsa bldltk-S-TI ll'll carry'a pairof CIEHHIJUpBidZhOIdGISf-iIM than-extend: along fQppOSiti. sides of tlieheated: barrSiltXEigureed): and have;channelshapedzcen sections":- inwhich: the: clamp pads? 60- are held;-; Iilietclampr pad"; holders: I .Iit: areemounted; fonmoyement towardiandzaway fromithe cylinder? 302cmguide bolts-i I I69; but are? normally; held? against" thexblocks" bysprings I I B.

To: insure. properrengagement of: the? pads; 69; witlirthecylindercoverxpad:755;. the? surfaces: of? the: pads: 6.0: that: face:the. cylinders: surface: are: slantedl'iat 2L5 slight P angles to each.other soias to lie:- parallel 1 to; planesir tangent: to; the; cylinder:surface at: theipoint'szxwhere. the "pads: 59; engage the?bags-"forming: material; This; arrangement can: be best: seenein:Eigurei '7, wherein. it is also evid'ent'zthatawhenz thei-heated bar; 58an'd'clampz pads; BIkareout of: engagement Withi the cylinder surface,=:the-clamp: pads; Sits-areasomewhat closer thanrthezheatedtbarto--thessuriaccilia";w Normally; theizmechanism 1'32? isi-held"away-from-zthe cylinder. 30.;ain :thei positionishownain Figure; 7;b'yJsprings I (Figure 3) acting against stops-*- IZZiomtha cam-z ITICIS:62;.

As: the-*camming: mechanism acts on-I the rods 62:. to'smove therheatz.sealingr'assembly: 32:: toward the. sealing cylinders: surface; thefirst: parts to: contact the cylinder: cover: pad: and; plastic; tube.I2 will be the: clamp; pads16fl'.=; Asiath'ei rods 62"? continue xtoz.move: radially: against the I force? of thew-springs: I'M;v the: clamp"vpad: carriers: Ill will'move: away; from the: supportblocksa lzlilagainst the:- biasof v their holding; springs". I i832 allowing:the'rods. M to: continue-their: radialmovement; At th-iswpointi.tl'i'e-e parts will be; in? the: relative :positions. shownrin Figure-I8;,ami the mechanism :32 'wi'llbemoving: Witl'l the rotating. cylinder:-31).-

Gontinued movement; of: the rods: Me in the same direction eventually?will: bringt'th'e: heatedwith moving t'cylinder, and: also holding .ithe-- plastic tube securely to preventanyadistortion of: thebageformingazmaterials.

At the; endi;of aapredeterminediti avel of the byethrzamiatehngtm off.the: cam: segments 12 thefscanniollowenzrcllers:'Ifiewilllrideeofii'thezcam'; segments; releasing-sthecam rodsiGZeThet'spriiigss I205 then:will'i'fnrcei the? mechanism: 32 to: moveradiallmoutward'lm releasing wthez-heated bart'and:

clamp:padsdfromcengagement iWith the :cylindersurface: Thereuponi' the:mechanism 32. will drop: back:.by gravitationainiorce to its originalrestaposit'ion: imsreadinessafon'the next heat scale in'ge operation:

Ase-thee mechanismemz drops backs down to its starting; position,:, lfrzwill: tend: toil-pick up speed to:aniextentHthat-smight:wellioverstressthe mechanism as it is broughteto anvabruptustopat'its. rests.QOSiblOIlr. To: offset thief-tendency, as" well as toiassistzimgettingtthemechanism :32: started: moving: upward-1m the:-weights of the mechanism 32 impartially; offset :bn'a pair ofi'counterweights I flafixed to :theicylinden shaft-5tt-atzopposite:ends:thereof? (see': Figures; 1% and 2). In order: that thezcounterweightst IMi-WiILeXert'their. maximum e-ff'ect -whenri 13119,; mechanism: 32: isin; its lower= most or rest) position; the: weights" are: so fixed;towtheshaft 'fi thatw a-iline t-hroughathe shaft axis and-i the-ecenteitofrgravitygof the: Weights l I 241 will rn'alte anm.anglerofx about:135* degrees witha: line throughzitheishaftzaxis andwthet center ofgravity of? the mechanism 32. 1 Since: the rods 62-: make: an? angler:of: about 45 degrees with the vertical wh'em the mechanisme32e is": in1: its: r'est position, it; can berrseen that-:ther-counterweightsI24-"will haverthein:maximumeefiect whenthewmechanism. 3:2 i-is-zinitserestposition;iandawilhhave:practically: noieflfectwhenzth'eimechanism 5-32fisf attheuppermostsnointdn?itsrotational.movement: Accordingly;- thecounterwei'ghts'c I 24=wil1wassistin startil'lgithe mechanism-e 3 23upwardlm; will not: im-- pede-rth'e."beginningrofe the oIow-nwardmovement of ther mechanism;,. and: then will. gradually counteracttherweightmfzthesmechanism 32 as it nears: its rest?positioneimswinging; downwardly.

Tonbringrthwdownwardlyzswinging;mechanism Mitor a cushioned: stop,aazresilientbumper pad I Zfiflfilgnrezfiris positioned 2130'" contactthe heated bar support 9! when the mechanism:32 r-eaches their-restposition: i At; the-same time, as shown in: Figure: 3:; theeslidingfcollar car on the: shaft 59 rwill'wbe: caught and: held. againstfurther. rotations iby; a is spring; loaded catch. pin= I 28' which ismounted: om the: support; member 54'" to en:- fi fl a holef'wflinithercollarr-flange-:84. Since the co'l-lareell partial-1y? engagesthebell crank sunport Sit-- aspreviously; explained, it is" seenthat thelocking-motion of-Cthe pin I28 willprevent rebound/of: the heat sealing,mechanism 32 when ittstrikessthe:bumper:I261 When the next heat:scaling;operation-ebegins; V the collar 86 will be: moveddnwardly; andreleased;v from the. pin I '2-8ebeforef thewassembly 32: begins .to:swing up.- w-a rdlya' l: .Inaxmachineior. makinggplasticbags, means ionmoving: al'ncontinuousi web-r oizrplastic zmaterial tlirou hithemachineiatsiai-substantiallyconstant speed, rotatablyi mountedfcylinder:having" a resilient outerz covering'ancl positioned $01 that said:material passe's'i partially; around said cylindei in": contactwithizth'ez surface: thereof a clamping? n'd heat :sealingesmechanismmounted forirotationabout theta-xiszoffsaid cylinder; means to'zreeuitrentiyzrmovingesaidimechanism:into: and out?ofsiengalgementtwiththe surfaceofisaid"cylin den so ms-M361 clamp successive 'portio'ns ofsaid pta'stio materiall. between said" meclianism and mechanismr32 withvtliecylinder 30; as controlled tlies surface -ofii ia, cyfifidr henclamped thereto, said mechanism including clamp means adapted to engagesaid cylinder surface and a heated bar having an electrical heatingelement for heat sealing said plastic material when said material isclamped between said bar and said cylinder surface, said mechanism beingarranged to return by gravitational force to its original position whenreleased from engagement with said cylinder, a counterweight secured tosaid mechanism for rotation therewith and arranged to at least partiallycounterbalance the weight of said mechanism during rotation thereof, andmeans for cutting said plastic material adjacent each heat seal formedtherein.

2. In a machine for making plastic bags, means for moving a continuoustube of plastic material through the machine at a substantially constantspeed, a rotatably mounted cylinder having a resilient outer coveringand positioned so that said material passes partially around saidcylinder in contact with the surface thereof, a clamping and heatsealing mechanism mounted for rotation about the axis of said cylinder,means for recurrently moving said mechanism into and out of engagementwith the surface of said cylinder so as to clamp successive portions ofsaid plastic material between said mechanism and the surface of saidcylinder and cause said mechanism to ride upwardly with said cylindersurface when clamped thereto, said mechanism including (l) clamp meansadapted to engage said cylinder surface, and (2) a heated bar having anelectrical heating element for heat sealing said plastic material whensaid bar is clamped against said material, said mechanism being arrangedto return by gravitational force to its original position when releasedfrom engagement with said cylinder, a counterweight secured to saidmechanism for rotation therewith and extending from the axis of saiddrum at an angle to said mechanism such as to at least partiallycounterbalance the weight of said mechanism during rotation thereof, andmeans for cutting said plastic material adjacent each heat seal formedtherein.

3. In a machine for making plastic bags, means for moving plasticmaterial from which bags are to be formed through the machine at asubstantially constant speed, a rotatably mounted cylinder having aresilient outer covering and positioned so that said material passespartially around said cylinder in contact with the surface thereof, aclamping and heat sealing mechanism mounted for rotation about the axisof said cylinder, means for recurrently driving said mechanism radiallytoward and away from the surface of said cylinder so as to clampsuccessive portions of said plastic material between said mechanism andthe surface of said cylinder and cause said mechanism to be lifted byand move with said cylinder when clamped thereto, said mechanismincluding a heated bar having an electrical heating element therein forheat sealing said plastic material when said bar is clamped against saidmaterial, and means independent of said bar for clamping said mechanismto said cylinder surface, said mechanism being arranged to return bygravitational force to its original position when released fromengagement with said cylinder, a counterweight secured to said mechanismfor rotation therewith and so positioned with respect to said mechanismthat a line through the axis of said cylinder and the center of gravityof said counterweight makes an angled substantially 135 de-- grees witha line through said axis and the center of gravity of said mechanism,and means for cut-- ting said plastic material adjacent each heat sealformed therein.

4. In a machine for making plastic bags, means for moving a continuousweb of plastic material through the machine without interruption, arotatably mounted cylinder having a resilient outer covering andpositioned so that said material passes partially around said cylinderin contact with the surface thereof, a clamping and heat sealingmechanism mounted for rotation about the axis of said cylinder, meansfor recurrently driving said mechanism radially with respect to saidcylinder so as to clamp successive portions of said plastic materialbetween said mechanism and the surface of said cylinder and cause saidmechanism to ride upwardly on the surface of said cylinder when clampedthereto, said mechanism including a heated bar having an electricalheating element therein for heat sealing said plastic material when saidbar is clamped against said material, and clamp means independent ofsaid bar for holding said mechanism firmly at the point of first contactwith the cylinder surface, said mechanism being arranged to return bygravitational force to its original position when released fromengagement with said cylinder, brake means associated with said radialdrive means and arranged to stop rotational movement of said mechanismupon the return of said mechanism to said original position until saidmechanism is subsequently moved radially toward said cylinder surface, acounterweight secured to said mechanism for rotation therewith andarranged so as to at least partially counterbalance the weight of saidmechanism during rotation thereof, and means for cutting said plasticmaterial adjacent each heat seal formed therein.

5. In a machine for making plastic bags, drive means for moving plasticmaterial from which bags are to be formed through the machine at asubstantially constant speed, a shaft, a cylinder rotatably mounted onsaid shaft and having a resilient outer covering, said shaft beingpositioned so that said material passes partially around said cylinderin contact with the surface thereof, a clamping and heat sealingmechanism mounted on said shaft for rotation about the axis of saidcylinder and movable radially toward and away from said cylindersurface, means for recurrently moving said mechanism into and out ofengagement with said cylinder surface so as to clamp successive portionsof said plastic material between said mechanism and said surface andcause said mechanism to ride upwardly on said cylinder surface whenclamped thereto, said mechanism including a heated bar having anelectrical heating element therein for heat sealing said plasticmaterial when clamped against said material, said mechanism beingarranged to return by gravitational force to its original position whenreleased from engagement with said cylinder, a pair of counterweightssecured to said shaft at opposite ends of said cylinder and extendingfrom said shaft at an angle with respect to said mechanism such thatsaid counterweights at least partially counterbalance the weight of saidmechanism, and means for cutting said plastic material adjacent eachheat seal formed therein.

6. In a machine for making plastic bags, means for moving plasticmaterial from which bags are to be formed through the machine t t-asst'facethereof, "a clamping and heat sealing mechanism 'mounte'd "for"jrdtationfabdiit the axis ,'of said cylinder, means r arec rjrennydrivingsaid "mechanism radiallyj'toward andawa I from the surface ofsaid cylinder soias to clamp successive portions of said pl'a'stijcinateiialfbetwe'en "said mechanism and the surface, of said'icylinderj'and cause said mechanism to 'beliftdhyandmove "with saidcylinder when clamped thereto, said mechanism including a .heated bar"having "an electrical heating therein for heat sealing said plasticmaterm when said bar is clamped against said material, said mechanismfurther immdmgapa r 'iofcla'rnpingg pads positioned onopposite-*sidesOf' Said'heated bar with the surfaces of saidp'ads that faceysa'idcylinder surface being arranged at an an'gley'to each other, saidmechanism being arranged to return by gravitational force to itsoriginal position when released from engagement with said cylinder, andmeans for cutting said plastic material adjacent each heat seal formedtherein.

7. In a machine for making plastic bags, means for moving a continuousflat tube of plastic material through the machine at a substantiallyconstant speed, a rotatably mounted cylinder having a resilient outercovering and positioned so that said material travels part way aroundthe surface of said cylinder in contact therewith in moving through saidmachine, a clamping and heat sealing mechanism mounted for rotationabout the axis of said cylinder, means for recurrently driving saidmechanism radially into and out of engagement with the surface of saidcylinder to cause said mechanism to move upwardly along the pathfollowed by said cylinder surface when clamped thereto, said mechanismincluding a heated bar having an electrical heating element therein forheat sealing said plastic material when said bar is clamped against saidmaterial, said mechanism further including clamping pads arrangedparallel to and on opposite sides of said heated bar with the surfacesof said pads that face said cylinder surface being slanted so as to beparallel to planes tangent to said cylinder surface, said mechanismbeing arranged to fall by gravitational force to its original positionafter it moves a predetermined distance in contact with the surface ofsaid cylinder, and means for cutting said plastic material adjacent eachheat seal formed therein.

8. In a machine for making plastic bags, means for moving plasticmaterial from which bags are to be formed through the machine at asubstantially constant speed, a rotatably mounted cylinder having aresilient outer covering and positioned so that said material travelspart way around the surface of said cylinder in contact therewith inmoving through said machine, a clamping and heat sealing mechanismmounted for rotation about the axis of said cylinder, means forrecurrently moving said mechanism radially into and out of engagementwith the surface of said cylinder to cause said mechanism to moveupwardly on said cylinder surface when clamped thereto, said mechanismincluding a heated bar having an electrical heating element therein forheat sealing said plastic material when clamped against said material,said mechanism further including clamping pads independent or said'heatedfbar for holding daid mechanism firmly to said cylindersiirface, afrei'silient, helical, multi-con'ducto'r" cable' .e'xtending fromastationary'point ons'aidmachine in. he vicinity of'said cylinder'axistosaid heatedjbar, said inech'anismbeing arrangedto iallby gravitationalforce to its original position 'afterfit moves a predetermined distance'infcdntact with 'the surface ofsaid cylinder, ans meaiisfor'cutlti'said plastic material adjacent each heat sealform'ed'therein. v j I 9.In a machine for 'r'nakifig plastic bags,

means for moving plastic materiallfrom which bags are to be formedthrough the machine at a substantially constant speed, a shaft, acylinde'r rotatably mounted on 'said'shaft and having a resilient outercovering, said shaft being positionedso that said material travels partway around the 's'urface'of'said cylinder in contact therewith in movingthrough said machine, a clamping and heat sealing mechanisinmounted onsaid shaft for mission about the axis of said cylinder, means forrecurrently driving said mechanism radially into and out of engagementwith the outer surface of said cylinder to cause said mechanism to rideupwardly on said cylinder surface when clamped thereto, said mechanismincluding a heated bar having an electrical heating element therein forheat sealing said plastic material when clamped against said material,said mechanism further including clamping pads arranged on oppositesides of said heated bar with the surfaces of said pads that face saidcylinder surface being at an angle to each other, said mechanism beingarranged to fall by gravitational force to its original position afterit moves a predetermined distancein contact with the surface of saidcylinder, a pair of counterweights secured to the end shaft at oppositeends of said cylinder and arranged to at least partially counterbalancethe weight of said mechanism during rotation thereof, and means forcutting said plastic material adjacent each heat seal formed therein.

10. In a machine for making plastic bags, means for moving plasticmaterial from which bags are to be formed through the machine at asubstantially constant speed, a rotatably mounted cylinder having aresilient outer covering and positioned so that said material travelspart way around the surface of said cylinder in contact therewith inmoving through said machine, a clamping and heat sealing mechanismmounted for rotation about the axis of said cylinder, means forrecurrently moving said mechanism radially into and out of engagementwith the surface of said cylinder to cause said mechanism to moveupwardly on said cylinder surface when clamped thereto, said mechanismincluding a heated bar having an electrical heating element therein forheat sealing said plastic mate-. rial when clamped against saidmaterial, said mechanism further including clamping pads independent ofsaid heated bar for holding said mechanism firmly to said cylindersurface, a resilient, helical, multi-conductor cable extending from astationary point on said machine in the vicinity of said cylinder axisto said heated bar, said mechanism being arranged to fall bygravitational force to its original position after it moves apredetermined distance in contact with the surface of said cylinder, acounterweight secured to said mechanism for rotation therewith andarranged to at least partially counterbalance the weight of saidmechanism during rotation 11 thereof, and means for cutting said plasticmaterial adjacent each heat seal formed therein.

11. In a machine for making plastic bags, means for moving a web ofplastic material through the machine without interruption, a rotatablymounted cylinder having a resilient outer covering and positioned sothat said material passes partly around said cylinder in moving throughsaid machine, a clamping and heat sealing mechanism mounted for rotationabout the axis of said cylinder, means for recurrently moving saidmechanism radially into and out of engagement with the surface of saidcylinder to cause said mechanism to ride upwardly on the surface of saidcylinder when clamped thereto, said mechanism including a heated barhaving an electrical heating element for heat sealing said plasticmaterial when clamped against said material, said mechanism furtherincluding clamping pads arranged on opposite sides of said heated barwith the surfaces of said pads that face said cylinder surface beingslanted so as to 12 be parallel to planes tangent to the cylindersurface, a resilient, helical, multi-conductor cable extending from astationary point on said machine in the vicinity of said cylinder axisto said heated bar, said mechanism being arranged to fall bygravitational force to its original position after it moves apredetermined distance in contact with the surface of said cylinder, acounterweight secured to said mechanism for rotation therewith andarranged to at least partially counterbalance the weight of saidmechanism during rotation thereof, and means for cutting said plasticmaterial adjacent each heat seal formed therein.

LADISLAV MORAVEC.

ALFRED GANS.

References Cited in the file of this patent UNITED STATES PATENTS Number

